Electrooptic Bragg-deflection modulators: theoretical and experimental studies

We have studied the mechanism of Bragg diffraction in electrooptic thin-film lightguides and examined in detail the effectiveness of interaction between the electric field and optical field. Expressions for the full deflection voltage and the power per bandwidth are obtained and applied to various modulator structures using out-diffused, metal-diffused, epitaxial, and sputtered-film (electrooptic substrate) waveguides. An expression for minimum interaction length to ensure better than 30-dB extinction ratio is derived. The theoretical results are checked with experimental observations from an electrooptic substrate modulator we fabricated, and good agreement is obtained.

Simple semiquantitative determination of trace metal ions by use of reagent gel columns-II: determination of zinc with dithizone gel

Zinc(II) at the sub-ppm level was determined by using a column, packed with gel beads containing dithizone. The beads turned from green to pink when the sample solution containing zinc was passed through the column at pH 6.2. Various interfering cations were masked by the combined use of sodium thiosulphate, alpha'alpha-bipyridyl, hydroxylamine hydrochloride, N,N'-bis(beta-hydroxyethyl) dithiocarbamate and beta-dithiocarbaminopropionic acid. The length of the pink zone was proportional to the amount of zinc in the sample. With 0.01% dithizone gel, as little as 0.01 ppm of zinc could be determined in a 10-ml sample at a flow rate of 0.2 ml min .

The management of solitary thyroid nodules under local anaesthesia

A group of patients with solitary nodules of the thyroid were treated at the University of Malaya by surgery under local anaesthesia. This was done in order to expedite exploration of a potentially malignant condition. This group comprised 43 patients, and four cancers were found. The standard technique used was satisfactory from the viewpoint of both the patient and the surgeon. The pattern of this condition in a Malaysian population is documented, the technique used is described, and thyroidectomy under local aneaesthesia is discussed.

Ultrastructural evidence of the hepatotoxic effect of halothane in rats following in-utero exposure

Eight pregnant Sprague-Dawley rates were exposed to 10 ppm halothane 8 hours/day and 5 days/week throughout pregnancy. Liver samples were obtained from the pups for electron microscopy. Degenerative changes such as myelin-figure formation, focal-cytoplasmic degradation; fatty changes and cellular necrosis were observed. Leukocytic infiltration and phagocytosis of the cellular debris by Kupffer cells were also evident. The present investigation has demonstrated the hepatotoxic effects of halothane on the foetal liver. The role of halothane as an occupational hazard is considered.

Ultrastructural changes in the kidney following chronic exposure to low levels of halothane

Rats were subjected to chronic exposure to low levels of halothane (10 and 500 ppm for 8 and 4 weeks, respectively). The ultrastructural changes in the kidneys were studied. Animals exposed to 10 ppm halothane demonstrated chronic degenerative changes in the proximal convoluted tublues, including proliferation and membranous whirling of the basal infoldings of some epithelial cells and membranous degeneration of the mitochondria to form membranous bodies within the cellular cytoplasm. These pathologic changes were even more extensive and exaggerated in animals exposed to 500 ppm halothane. Fusion of the membranous bodies to form large membranous plaques and coalescence of lysosomes to form irregulary shaped cytoplasmic dense bodies were frequently found. Swelling of the mitochondria and areas of focal cytoplasmic degradation were also observed. Extrustions of large cytoplasmic masses containing mitochondria. clusters of smooth endoplasmic retriculum and ribosomes into the tubular lumen were frequently observed. Accumulation of spherical microparticles within the tubular basement membranes were also a prominent finding. The present investigation clearly indicated that halothane is nephrotoxic and may be considered as an occupational hazard.

Mortality in systemic lupus erythematosus: a 10-year review

During the years 1963-72 33 patients with systemic lupus erythematosus (S.L.E.) died. Of these 30 case records were available for analysis. For the same period 167 patients with S.L.E. were admitted. It was ascertained that of the 30 deaths 22 were directly attributable to the disease itself and 8 were related to complications of therapy. The three commonest causes of death were neurological involvement (11 patients), renal failure (9 patients), and infection (8 patients).

Lead poisoning from contaminated opium

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Hamster-tropic sarcomagenic and nonsarcomagenic viruses derived from hamster tumors induced by the Gross pseudotype of Moloney sarcoma virus

Hamster sarcomas induced by the Gross pseudotype of Moloney sarcoma virus yielded a virus sarcomagenic for hamsters but not mice. This virus was able to produce foci on hamster embryo cells, but not on mouse embryo cells. A hamster-tropic nonfocus-forming helper virus was also found in the viral stocks. These hamster-tropic viruses are not immunologically related to the murine viruses in the original inoculum but appear to represent indigenous C-type RNA viruses of the hamster.